As above, the invention relates to novel yarns and threads (using these terms broadly, as explained further below) that can be expanded after being woven into fabric, or used to fabricate various useful products, and thereafter expanded. Such yarns and threads can be used to fabricate various novel and useful products.
For example, “papermaker's felts” are, generally, woven fabrics used to manufacture belts supporting a wood-fiber slurry in manufacture of paper. It is important to control the porosity of the woven fabric, as its porosity controls the rate at which water is removed in the drying process, which is a critical step in the papermaking process. The porosity of a papermaker's felt is largely related to the diameter of the “yarns” or threads from which it is woven, but this cannot be chosen independent of all other variables, such as the feasibility of weaving, the strength of the fabric, and so on. A yarn the diameter of which could be altered after weaving would be a very useful product, since it would expand the flexibility available in specification of the fabric; that is, the fabric could be woven and the yarns subsequently expanded to reduce the porosity of the fabric.
Similarly, in manufacture of many sorts of goods which are sewn together, such as tents, awnings, clothing, sails, shoes, and many other products, the sewing process involves the puncturing of many holes in a fabric or other material which desirably would be waterproof and (in many case) air-impermeable. A thread which could be expanded after fabrication of the product, sealing these holes, would be very useful.
Other uses for expansible yarns according to the invention are discussed below.
A search for prior art patents directed to the invention, as described more fully below, identified the following:
Muskat U.S. Pat. No. 2,879,197 shows a method for making a foamed resin pad in which a fibrous batt is impregnated with a foamable resin; the product produced is a pad, e.g., for mattresses or the like. At col. 7, lines 9-25 the application of covering materials is described. Muskat does not seem to suggest using the expanding qualities of the foam material as a positive step in forming a product. An earlier-filed Muskat patent, U.S. Pat. No. 2,972,554, is closely related.
Dalle U.S. Pat. No. 3,072,512 shows making a reinforced sheet material, for manufacture of food bags and the like, wherein PVC-coated and uncoated nylon threads are heat-welded to sheet PVC.
Richmond U.S. Pat. No. 3,100,926 shows forming fabric from thread comprising a thermoplastic and a blowing agent, and heat-treating the fabric to cause the blowing agent to cause the thermoplastic threads to expand, and simultaneously causing the thermoplastic threads to adhere to one another.
Hagelin U.S. Pat. No. 3,451,696 shows a method for sealing the joints of ducts. An expandible sealing member, comprising, e.g., neoprene rubber mixed with expanding and curing agents, is assembled into the joint along with a pyrotechnical agent. The latter is then ignited, to cause the rubber mixture to expand and cure.
Wisotzky U.S. Pat. No. 3,574,020 shows vinyl-coated fabrics, in particular for controlled embossing processes.
Clough U.S. Pat. No. 3,646,749 shows metallized fabrics.
Proucelle U.S. Pat. No. 3,980,511 shows manufacture of panels for sound insulation purposes. Glass fibers are impregnated with a thermoplastic including an expanding agent; this is then heated to expand the plastic. After cooling the material is elastic.
U.S. Pat. No. 4,144,371 to Okie and Worrall shows fabrics made of a thread comprising single or multi-filaments encapsulated with a plastisol, which comprises PVC mixed with a foaming agent. The fabric is heat-treated after weaving to cause the threads to expand and weld to one another.
U.S. Pat. No. 4,197,345 to Worrall shows fabrics woven of threads at least some of which are made as in the Okie and Worrall patent, to provide contrasting colors.
U.S. Pat. No. 4,243,713 to Worrall and Auger shows fabrics woven of threads which have first and second plastisol coatings of different colors, to produce variegated color effects upon expansion for the foaming agent.
U.S. Pat. No. 4,520,059 to Worrall and Tefft shows fabrics, in particular papermaker's felts, made from a synthetic yarn such as nylon which is covered with an ionomer resin.
U.S. Pat. No. 4,731,281 to Fleischer also shows a papermaker's felt, woven from encapsulated or coated monofilament yarns.
U.S. Pat. No. 5,124,194 to Kawano shows microfibers made from hot-melt adhesive, having an “island-in-sea” structure.
U.S. Pat. No. 5,204,150 to Davenport shows a coated multifilament yarn for use in weaving on-machine-seamable press fabrics. The core material of the yarn is a polyamide thermoplastic and the coating can be a urethane or acrylic, if a permanent coating is desired; other materials are given for temporary or semipermanent coatings. U.S. Pat. No. 5,391,419, also to Davenport, is closely related.
Finally, published patent application 2005/0064776 to Sobonya shows sheet material, for use as a shelf liner or the like, comprising a scrim in a foamable resin, e.g., a PVC plastisol.